Authorities in Japan are now reporting that fuel rods are melting at the 3 crippled reactors.  Their containment vessels are still intact preventing a catastrophic radiation release.  It shows that Japanese authorities attempts to cool the reactors have failed so far.  They have reported that up to 180,000 have been evacuated.  Newer experimental reactor designs like Pebble Bed Reactor’s are virtually meltdown proof.  These older GE Mark 1 BWR require massive cooling 

networks and piping.  It is the cooling network that has shown to its Achilles heel.  The nuclear plant at Chernobyl was a disaster because it did not have a containment vessel.  After the meltdown a fired raged for days as the authorities proclaimed that there was no problems.